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Impact of Planting Date on Corn Yields in North Dakota (05/10/18)

Last week in my Crop and Pest Report, I discussed the effect of late planting on spring wheat yield. Substantial progress in wheat planting was achieved this past week (from 3% to 20%), nevertheless the area planted is still significantly less than last year and the five year average. Hopefully the weather will allow for continued progress in planting this coming week.

Impact of Planting Date on Corn Yields in North Dakota

Last week in my Crop and Pest Report, I discussed the effect of late planting on spring wheat yield. Substantial progress in wheat planting was achieved this past week (from 3% to 20%), nevertheless the area planted is still significantly less than last year and the five year average. Hopefully the weather will allow for continued progress in planting this coming week.

According to the most recent NASS data (week ending May 6th), only 7% of the corn area had been planted in North Dakota. This compares to 20% last year and 24% for the five-year average. The recommended planting date for corn for all regions of the state is May 1st (or more realistically the first two weeks in May). Because corn is a warm season crop, it will not grow when temperatures are below 50 degrees, so when soil temperatures remain below 50 degrees after planting there is little growth regardless of the calendar date. When planting is delayed beyond the middle of May, the risk of the crop being killed by frost in the fall before it reaches physiological maturity increases, as does the chance that the grain will be wet, difficult to handle, and expensive to dry. Dr. Franzen’s article this week provides information on the type of losses that can occur as corn planting is delayed. These data are based on small plot research over multiple seasons and therefore estimate average losses; losses in a given seasons may be less or more than those listed.

Similar to what I did last week for wheat, I examined the relationship between planting date and final yield for the past 10 year on a statewide basis using planting progress and final yield data from NASS. The relationship between the date when 50% of the corn area in the state had been planted and yield that year are summarized in the graph on page 7. For the purposes of this article, to fix a 50% planted date, I extrapolated between the NASS reporting dates when there was less than 50% planted and when there was more than 50% planted. The yield values were those reported for the state as a whole.

chart.ransom

Unlike what was found for wheat where there was little relationship between planting date and yield, in corn this relationship was more pronounced. The equation from this relationship suggests that for every day delay in planting beyond May 3rd, yield is reduced by about 1.1 bu per day. This yield loss is roughly in line with the results from the smaller plot research reported in Dr. Franzen’s article. The final planting date for full insurance coverage for corn in North Dakota is May 25th, except for Cass, Ransom, Richland and Sargent counties where the final planting date is May 31st.

These data show the importance of planting corn early. However, planting date is not the only determinant of yield and in fact only explains about 30% of the yield in the above graph. This means that regardless of planting date, weather and management play a critical role on yield. Establishing a uniform stand is a critical practice in developing a foundation for high yield. Therefore, even though we are nearing the end of the optimum planting period for corn, don’t be in such a rush that plant stand uniformity is compromised. In addition to temperature, soil moisture, planting speed, and crop residues have been shown to impact corn emergence. Interestingly in some survey work that we did a few years ago, the speed of the planter was found to be one of the most important determinates of variability in emergence. Since crop residues can influence soil temperature (and uniformity of emergence), make sure trash managers are working and properly adjusted. Seeding depth can also play a role in emergence variability. Provided there is moisture, seeding at 1.5 to 2 inches seems to work best for establishing a uniform stand in most environments.

Joel Ransom

Extension Agronomist for Cereal Crops

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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